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Cyclonephelium crebrum
From Fensome et al., 2019:
Cyclonephelium crebrum Duxbury, 2019, p.186, pl.16, figs.7,11–13. Holotype: Duxbury, 2019, pl.16, figs.7,11–13. Age: late Barremian.
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Original description: [Duxbury, 2019, p. 186]:
Cyclonephelium crebrum Duxbury n. sp.
Plate 16, Figures 7, 11–13 Cyclonephelium sp. II HARDING 1990, p. 20, pl. 3, figs. 7–9
Holotype: Plate 16, Figures 12, 13.
Type Locality: Heslerton No. 2 at 22.95 m (core chip), late Barremian age. Holotype: E.F. R42.1.
Derivation of Name: From the Latin creber, thick, crowded, packed, close set – in reference to the surface ornament.
Diagnosis: A dorso-ventrally flattened, single-walled species, sub-circular in outline with a prominent left antapical bulge. The surface is covered with numerous short, capitate spines which are much reduced or absent in the mid-dorsal area and which are transected by a deep, diagonal depression on the ventral surface. Increases in ornament height occur on the left antapical bulge and its right antapical equivalent. Ventral reduction in ornament height continues beyond the sulcus so that in lateral view a break in ornament usually occurs at the cyst margin. Archeopyle tetratabular apical with the operculum usually lost, leaving a zig-zag margin with slight sutural splitting suggesting six precingular plates. No tabulation apparent except for the archeopyle margin.
Dimensions: Holotype: Length - 73 µm. Width - 78 µm.
Overall: Length - 84 (73) 63 µm; Width - 86 (77) 63 µm.
Specimens Measured: 4 (operculum detached). Remarks: As noted by Harding (1990, p. 20), this species is usually rare, occurring in low numbers in Heslerton No. 2 between 26.00 m and 20.00 m (late Barremian), being consistently present between 26.00 m and 22.95 m; a similar, very short range to that reported by Harding. It was more common at the top of its range at 11,181.33 ft and 11,179.50 ft in well 22/26a-2, however. It is a distinctive form, particularly in having a very dense cover of spines and a well-defined sulcal/post-sulcal “bald” area. The wide geographic range of this species reported by Harding (op. cit.) and its very short stratigraphic range suggest that it might be a valuable marker for the late Barremian; its LAD in well 22/26a-2 falls within palynofloral Subzone LKP23.1.
This species is similar to Cyclonephelium distinctum Deflandre and Cookson 1955 but, as noted by Harding (1990, p. 20), “with a greater density of more slender processes concentrated in marginate areas” (compare Plate 16, Figures 7, 11-13 with Plate 16, Figure 4).
Cyclonephelium crebrum Duxbury, 2019, p.186, pl.16, figs.7,11–13. Holotype: Duxbury, 2019, pl.16, figs.7,11–13. Age: late Barremian.
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Original description: [Duxbury, 2019, p. 186]:
Cyclonephelium crebrum Duxbury n. sp.
Plate 16, Figures 7, 11–13 Cyclonephelium sp. II HARDING 1990, p. 20, pl. 3, figs. 7–9
Holotype: Plate 16, Figures 12, 13.
Type Locality: Heslerton No. 2 at 22.95 m (core chip), late Barremian age. Holotype: E.F. R42.1.
Derivation of Name: From the Latin creber, thick, crowded, packed, close set – in reference to the surface ornament.
Diagnosis: A dorso-ventrally flattened, single-walled species, sub-circular in outline with a prominent left antapical bulge. The surface is covered with numerous short, capitate spines which are much reduced or absent in the mid-dorsal area and which are transected by a deep, diagonal depression on the ventral surface. Increases in ornament height occur on the left antapical bulge and its right antapical equivalent. Ventral reduction in ornament height continues beyond the sulcus so that in lateral view a break in ornament usually occurs at the cyst margin. Archeopyle tetratabular apical with the operculum usually lost, leaving a zig-zag margin with slight sutural splitting suggesting six precingular plates. No tabulation apparent except for the archeopyle margin.
Dimensions: Holotype: Length - 73 µm. Width - 78 µm.
Overall: Length - 84 (73) 63 µm; Width - 86 (77) 63 µm.
Specimens Measured: 4 (operculum detached). Remarks: As noted by Harding (1990, p. 20), this species is usually rare, occurring in low numbers in Heslerton No. 2 between 26.00 m and 20.00 m (late Barremian), being consistently present between 26.00 m and 22.95 m; a similar, very short range to that reported by Harding. It was more common at the top of its range at 11,181.33 ft and 11,179.50 ft in well 22/26a-2, however. It is a distinctive form, particularly in having a very dense cover of spines and a well-defined sulcal/post-sulcal “bald” area. The wide geographic range of this species reported by Harding (op. cit.) and its very short stratigraphic range suggest that it might be a valuable marker for the late Barremian; its LAD in well 22/26a-2 falls within palynofloral Subzone LKP23.1.
This species is similar to Cyclonephelium distinctum Deflandre and Cookson 1955 but, as noted by Harding (1990, p. 20), “with a greater density of more slender processes concentrated in marginate areas” (compare Plate 16, Figures 7, 11-13 with Plate 16, Figure 4).